Many mobile wireless electronic devices of today can communicate with surrounding devices and thus act as nodes in an ad hoc network. Ad hoc networks are spontaneous, self-configuring networks with no fixed infrastructure, which may be formed when electronic devices are in the vicinity of each other. Nodes may enter into, or exit from, an ad hoc network as the different devices approach or move away from each other, respectively. The nodes forming an ad hoc network are normally on a par with each other, so that none of them have a different responsibility for the transmission within the network than the other nodes. Typically, a node in an ad hoc network is a portable, battery-powered device such as a lap-top computer, a personal digital assistant, an MP3 player or a multimedia mobile phone.
A node in an ad hoc network can be made to exchange information with another node in the ad hoc network, see e.g. M. Jacobsson et al., “Push!Music: Intelligent Music Sharing on Mobile Devices”, The 7th International Conference on Ubiquitous Computing, September 2005, wherein a system for pushing music files from a first node in an ad hoc network to another node in the ad hoc network is disclosed. The pushing of music files may be initiated by the user of the first node, or by an agent file software in the first node, which can compare the listening pattern of the first node to that of other nodes in order to identify similar listening patterns and hence potential receivers of the contents of the first node.
Another disclosure of information exchange in an ad hoc network is given in Bach et al., “Bubbles: Navigating Multimedia Content in Mobile Ad-hoc Networks”, Proceedings of the 5th Wireless World Conference 2004, Surrey, UK. A system is disclosed wherein a software application in a first node in an ad hoc network can detect when other devices are in the proximity of the node. When another device has been detected, the application in the first node shows a list of available music files in the other device. The end user can then initiate download of information from the other device to the first node via unicast (peer-to-peer) communication.
One of the benefits of information exchange between nodes in an ad hoc network is that the different users of nodes in an ad hoc ad network often know each other (since the nodes were brought in the vicinity of each other), and therefore, the chances that the contents of one node would be interesting to users of the other nodes is high. However, multimedia files, such as music or film files, are often very large. Transmissions of such files between nodes in an ad hoc network are therefore time and/or bandwidth consuming. Since the transfer of large files between nodes generally takes a long time, the power consumed during the transfer of a file is large, which is especially undesirable as the nodes are typically battery-powered. A method that can provide efficient transmission of information between nodes in an ad hoc network is therefore desired.